Too Many Bases Exceed the Drive Budget - Electronic Circuits XI: Transistor Switching and Device Regions Step by Step

Fanout fails when summed base current exceeds the driver limit. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Seven half-ampere bases need seven-halves amperes

Seven base inputs at 1/2 A each sum to 7/2 A.

7\cdot {1\over 2}\ \text{A}={7\over 2}\ \text{A}

Above the driver limit, the budget fails

The total 7/2 A is greater than the 3 A driver limit, so this fanout is rejected.

{7\over 2}\ \text{A}>3\ \text{A}